Ultra wideband (UWB) communications are emerging as an important protocol for providing high speed, low power, and multi-path resilient communications. UWB signals consist of a train of extremely narrow pulses, typically on the order of 0.2-2.0 nanosecond (10−9 s). Usually, the transmitted pulse (typically Gaussian in shape) represents the modulation or baseband data, and accordingly, UWB systems are sometimes referred to as “carrier-less” systems, as the modulation signal is not translated to another frequency for transmission. Further, as the pulse width is very short compared to the pulse period, UWB signals occupy a very broad communication band at low power levels, making signal recovery extremely challenging.
FIG. 1 illustrates an exemplary Gaussian signal UWB receiver known in the art. The system 100 includes a UWB antenna 102, front-end filter 104, front-end amplifier 106, correlator 110, and backend circuitry 120. During reception, a UWB signal 101 is collected by the UWB antenna 102, and front-end filter 104 operates to limit the input bandwidth and reduce signal strength at image frequencies. Front-end amplifier 106 provides additional signal strength with some addition of noise. Importantly, the front-end amplifier 106 is required to provide sufficient gain over the entire UWB bandwidth, which may extend 1-7 GHz (×109 Hz). Such a large gain-bandwidth product is difficult to provide, and typically results in degraded performance over the entire UWB bandwidth as compared to the amplifier's performance over a narrower band. The front-end amplifier's marginal performance places a high signal to noise ratio (SNR) requirement on the correlation for adequate receiver performance.
What is needed is an improved UWB receiver architecture which is operable to provide the necessary signal gain while preferably reducing the SNR required from front-end amplifier and correlator.